Field of the Invention
The present invention relates to a power amplifier module.
Background Art
In a mobile communication device such as a mobile phone, a power amplifier module is used to amplify the power of a radio frequency (RF) signal to be transmitted to a base station. For example, in GSM® (Global System for Mobile Communications), the gain of the power amplifier module is controlled to realize the slope control (ramp up and ramp down) of a transmitting signal from the mobile communication device to the base station.
For example, Patent Document 1 discloses a configuration for supplying voltage VLDO output from an LDO (Low Drop Out) regulator to a collector terminal of each stage of a three-stage amplifier in a power amplifier module. In this configuration, the level of the voltage VLDO is adjusted based on control voltage VRAMP to control the gain of the power amplifier module.
Patent Document 2 discloses a configuration in a power amplifier module including a three-stage amplifier, where voltage VREG output from an LDO regulator is supplied to first stage and second stages, and constant power-supply voltage is supplied to a third stage.